The diseases caused by mycobacteria are a major world-wide health problem with over 27 million cases annually. The pathogenicity and clinical detection of mycobacterial infections are closely tied to the host's immune response to the mycobacterial antigens, which are as of yet poorly defined. We propose to characterize these antigens at the molecular level in order to produce a clearer understanding of the immunologic structure and, hence, pathogenicity of the mycobacteria and possibly to generate reagents or protocols that might form the basis of immunodiagnostic assays for the detection of mycobacterial infection and for the rapid and accurate identification of the infecting species. Given that the current clinical procedures can take weeks to positively identify the infecting species, such an immunoassay could speed up the diagnosis of disease and, hence, directly improve patient management. The basic approach will be first to dissect the immunologic structure of the mycobacteria by isolating and characterizing a series of monoclonal hybridoma antibodies directed against the various mycobacterial species. The target antigens will be purified by immunoaffinity chromatography and assayed for the biologically important features of antigenicity and immunogenicity. An important portion of this project will involve cloning and sequencing of the genes that encode the species-specific protein antigens identified by the above studies. From the nucleotide sequences it should be possible to deduce the amino acid sequences of the antigens which in turn can be used as blueprints to direct the chemical synthesis of oligopeptides. The peptides will be used to investigate the antigenicity and immunogenicity of portions of the mycobacterial antigens. The antibodies, purified antigens or synthetic peptides could be valuable reagents for the detection of mycobacterial disease.